Piston for internal-combustion engines



June 18, 1929. c. H. WILLS PISTON FOR INTERNAL COMBUSTION ENGINES FiledOct. 13, 1924 Patented June 18, 1929.

UNITED STATES PATENT OFFICE.

PISTON FOR INTERNAL-COMBUSTION ENGINES.

Application filed October 13, 1924. Serial No. 743,254.

My invention relates to pistons for internal combustion engines and anobject of my improvements is to lessen their range of variationtemperature in use. I

I se re this object among others in the device illustrated in theaccompanyingdrawa, indicatesthe piston as a whole. 0, 0,

are thegrooves for the packing rings and 20. b, b, are the rings in thegrooves c, c.

The piston is made of non-ferrous metal such as aluminum alloy, ormagnesium alloy, and is of the usual hollow construction open at itslower end toward the crank case. The upper part of the interior wall isprovided with. ridges e, which in this instance have the shape of coarsescrew threads, and the end wall is provided withridges of a similarshape in cross section extending -0 across said wall. These ridges areformed by providing a sectional core divided into parts v as indicatedby the lines It and m, Fig. 2,

forming a coarse screw thread on its cy1in-' drlcal surface andtransverse ridges, on its.

end. After the piston has been cast the central piece of the core isremoved directly, after which the other parts of the core may beseverally moved inward to disengage-them from the casting and thenremoved directly from the mold. i

d, is a shell of iron placed upon the outer cylindrical surface of thepiston by elec trodeposition and over the interior wall surface. Theiron shell extends over thewalls ofthe-ring grooves and over thesurfaces of the ridges e and, f. The thickness of the shell is muchexaggerated in the drawing. The upper end ofthe piston is a nonabsorbentof radiant heat. It may be of the same material as the body of thecylinder piston all metals that are nonabsorbent of structing joint.

ind polished and bright to reflect the radiant eat. Y

The iron shell is adapted to radiate heat readily, and also to form adurable wearing surface at the portion that comesin contact with thewall of the cylinder.

The rings, 7), b, are of iron and receive heat by contact with the wallsof their grooves and they also absorb heat radiated rom said walls andimpart the heat thus received to the cylinder walls 71. and lubricating,oil by contact and radiation.

The iron forming the inner surface of the piston radiates heat readily,which radiated heat is absorbedby'the small particles of lubricating oilfloating as a mist in the interior of the piston.

The ridges e and f present a large cooling surface which is washed bythe material dashed into the piston by the rotation of the cranks. v

With the above described construction the range of temperature variationis so small "that the piston expands with the iron cylinder and theclearance may be small.

While I have-described a particular construction for increasing the areaof cooling surface, as ridges e and f, clearly other forms extendingover a considerable portion of the interior of the piston may besubstituted therefor. I Nonabsorbent is of course a relativeterm asreferring to the action of a substance, or

surface, exposed to heat.

lVhile' for distinctness I have defined my invention in the claims asconsisting of a piston of nonferrous material with iron depositedthereon by electrodeposition I claim a range of equivalents for themetal of the I radiant heat, and for the covering metal all metals thatare good radiators of heat when they are intimately united with themetal of thepiston, so as to obviate any heat ob- What'I claim is v v 1.A hollow piston having-an uncovered cylindrical inner surface andacooling ridge for dissipating vthe heat therefrom, said ridge beingshaped in a spiral form whereby m0 the said ridge may be best with thepiston bustion engine of nonferrous metal, such as and the pattern beremoved by turning. aluminum ormagnesium, havin the walls 10 2. A pistonfor an internal combustion of its hollow portion covered w1th iron byvengine of nonferrous metal, such as alumielectrodeposition. num ormagnesium, having its outer cylin- In testimony whereof, I sign thisspecifidrical surface covered with iron by eleocation. trodepositionthereon.

3. A, hollow piston for an internal como. HAROLD WILL-S.

